Some questions about the Cassini-Huygens mission

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aerogi

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First I'd like to point out, that the results so far we got from this mission (both Cassini and the lander) are far better than what I've expected before, so I am not one of those who are utterly dissappointed... But anyway I have a few questions about this mission:<br /><br />1/Cassini has a power supply from which it can survive for many years (I've read somewhere even 200 years!). So why didn't they equipped the Huygens probe with a similar power supply so it could had a little longer life on this moon, maybe long enough to be able to submit more Megabytes of data?<br /><br />2/The Voyagers were able to take fairly good detailed pictures of all of Saturn major moons during a flyby passage. So we have Cassini in orbit (!), yet it only seems to take pictures when it comes very close of a moon. It does take some others pics, but mostly very distant. It's hard to explain what I mean, but I hope you get my point.<br /><br />3/Is there a possibility, after a few years of exploration of the Saturn system, that the spacecraft could be 'thrown out of this system' to go back and travel to the Jupiter system and try an orbit insertion there? That might be too difficult, but maybe just a flyby to one of the moons and have the most detailed pics ever of Europa or Io?<br /><br />4/ point 3 would probably be a 'no' for answer, so what are the possibilities at the end of this mission? I understand 'plunging' into Titan is not an option (contamination reasons), so most likely it will be a Saturn 'plunge'. But I'd rather would like to see them doing a 'manoeuvre' to try to 'soft' land it on another moon, like they did with the NEAR mission. Maybe on that strange 'walnut' like moon? And taking pics during the approach, and with a bit of luck it might be able to continue taking pics after the landing.<br /><br />5/Cassini has such an advanced radar mapping system, but for some reason, to my untrained eye, I can't make up anything from these pics. I don't know what colours should make the elev
 
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najab

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><i>So why didn't they equipped the Huygens probe with a similar power supply so it could had a little longer life on this moon, maybe long enough to be able to submit more Megabytes of data?</i><p>As it turned out, battery life wasn't the limiting factor, it was geometry. Hygens was severely mass limited - they had to shave every gram that they could. One way they did this was by using Cassini to relay the data back to Earth, rather than having to have a powerful (and therefore large) radio transmitter on the probe. This meant that they could only transmit to Earth while Cassini was 'in the sky' from Hygens' landing site. Hygens actually transmitted for a couple hours after Cassini went over the horizon but that data was lost.<p><i>The Voyagers were able to take fairly good detailed pictures of all of Saturn major moons during a flyby passage. So we have Cassini in orbit (!), yet it only seems to take pictures when it comes very close of a moon. It does take some others pics, but mostly very distant.</i><p>Have patience, the Cassini mission is going to be a <b>long</b> one. In time they will be many close passes of each of the major moons. The reason that Cassini's images might seem to be less impressive than those taken by the Voyagers is that Cassini's cameras sacrifice some spatial resolution for spectral. The VIMS camera doesn't have a huge number of megapixels, but it is <b>very</b> sensitive across a wide spectrum. The result is we don't get the biggest pictures, but we do get much more data out of each image.<p>><i>Is there a possibility, after a few years of exploration of the Saturn system, that the spacecraft could be 'thrown out of this system' to go back and travel to the Jupiter system and try an orbit insertion there?</i><p>I've read that there is a <b>very</b> slight possibility that, over the course of several orbits, they could put Cassini into a Saturn centred orbit that intersects Neptune, but I've never heard anything about Jupiter.<p>><i>4/ poi</i></p></p></p></p></p></p>
 
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yurkin

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Hi Aerogi<br /><br />Welcome to space.com<br />Regarding question 1, in addition to what Najab said…<br />A nuclear power source, like the one Cassini had, and an antenna that can transmit to Earth would have taken up pretty much the entire mass of the Huygens capsule. <br /><br />2. It was almost three years after the Jupiter Flyby that the full, true color, image enhanced, Picture of Jupiter was released. So one must be patient.<br />http://saturn.jpl.nasa.gov/multimedia/images/image-details.cfm?imageID=667
 
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vogon13

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Thousands of Saturn trajectories were considered for the Voyager flybys, as you can imagine, NASA/JPL was highly motivated to pick excellent paths that approached multiple satellites. Cassini is returning to Titan virtually every orbit for orbit mods, Huygens support, etc. This is a large constraint on were you go because if you don't return to Titan, you can no longer easily mod your orbit. Essentially, for the time being, as far as the other satellites are concerned, we are encountering the satellites by chance. Later Titan flybys will direct Cassini to other satellites, but always on a path that eventualy returns to Titan. To bad there aren't more of these orbits that encounter multiple satellites on each pass, but keep in mind the Saturn system is big and JPL is trying to hit all objects of interest. Oops, fly by all objects of interest.<br /><br />I think many of those distant satellite photos are optical navigation pictures that are quite necessary to set up these interesting satellite flybys. <br /><br />The Radar instument is a fairly short range device, especially in imaging mode (I presume you want to look at ring boulders) and Cassini has already made its closest (primary mission) ring approach. And I don't think that approach was close enough except maybe at ring plane crossing. Sorry, nice idea, we'll put it on next Saturn JIMO derived probe.<br /><br /><br /><br />There are 37 ways to skin a cat.<br />LIS Robot<br /><br /><br /><br /><br /><br /><br />r <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>
 
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vogon13

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Re: Radar observation of saturn ring structure<br /><br />Upon further thought, radar instrument looking at Saturn's rings in imaging mode most likely would be hampered (even if close enough) by relative motion of ring particles to each other during radar sweep. Seem to recall Fourier techniques used in radar analysis of scan data, if particles move significantly during scan I think it screws up the calculations. Radar seems to barely work on a solid continuous surface, probably need some kind of iterative approach to image presumably 3D collection of boulders in motion. Sounds like another gadget for the follow on Saturn Prometheous Mega Probe. <br /><br /><br /><br />But you met another, and pltttth, you were gone.<br />HeHaw <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>
 
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CalliArcale

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Cassini's fantastic Saturn tour is divided into segments based on the orbital mechanics and the intended goal of each segment. They've got a nice "petal plot" (attached to this post) showing each phase color-coded. "Petal", incidentally, refers to one of Cassini's orbits around Saturn. They are highly elliptical, and thus look like petals. <img src="/images/icons/wink.gif" /> Here is an overview of each major phase of the mission. Note that a specific tour of the icy moons is already planned for 2007. It is not priority that sets the schedule here, however. It's all about orbital mechanics.<br /><br /><br />SOI & Probe Release (white)<br /> * 7/1/04 - 2/15/05<br /> * SOI - orbit 3<br /><br />Occultation Sequence (orange)<br /> * 2/15/05 - 9/7/05<br /> * orbits 3-14<br /> * this sequence is intended to study the rings, by setting up a series of<br /> occulation events. It has to happen early, while the rings are "open"<br /> as observed from Earth, so that Cassini can see Earth be occulted<br /><br />Petal Rotation/Magnetotail Petal (green)<br /> * 9/7/05 - 7/22/06<br /> * orbits 14-26<br /> * this sequence shifts Cassini's orbit so it passes through a large swath<br /> of Saturn's magnetosphere and magnetotail; this will be a major period<br /> for plasma wave sciences <br /><br />Titan 180 Transfer (blue)<br /> * 7/22/06 - 6/30/07<br /> * orbits 26-47<br /> * shifts Cassini's orbit relative to Titan's so that Cassini can encounter<br /> Titan on the outbound legs of its orbits; this lets scientists capture<br /> different views of Saturn and also enables studies of the opposite face<br /> of Titan<br /><br />Rotation/Icy Satellites (yellow)<br /> * 6/30/07 - 8/31/07<br /> * orbits 47-49<br /> * close flybys of the icy satellites to study them in detail<br /><br />High Inclination Sequence (red)<br /> * 8/31/07 - 7/1/08<br /> * orbits 49 - end of mission (hoped to hit at least orbit 74)<br /> * this sequence shifts the inclination of Cassini's orbit so it can study<br /> Sat <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>
 
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